Personally I'd hang fire for a bit since both AMD and Intel are due to swap to a different socket again.

The new AMD M2 socket will for the new 64bit range of cpu's with full support for DDR2. Though AMD have hinted they'll swap to DDR3 sooner rather than later.

Intel are bringing dual core pentium-m architecture to the desktop with Yonah and then progressing through Woodcrest, Conroe and Merom by the 2nd half of 2006. All of these are planned for Socket 479 which Yonah is already running on.

If your sticking with a P4, then get a board with a Alderwood (Intel 925x) or Grantsdale (Intel 915) chipsets, both are socket 775. These are the only two chipsets worth looking at for DDR2 on an Intel platform. If your on AMD then you cant get a DDR2 solution since current AMD chips don't support it.

As an off point theres sod all in DDR2 over standard DDR when it comes to most tasks. Have a look here and flick through the DDR vs DDR2 tests, you gain or loose 2 or 3 fps in games and encoding etc, in a lot of cases standard DDR is faster! Soooooo... might be better off investing in some fast DDR ram, DDR2 latencies are shocking and make it more or less pointless.